In this paper, we provide possible vulnerabilities of the algorithm set forth by Mohamed Amin et al. [Commun. Nonlinear Sci. Numer. Simulat. 15, 3484-97, (2010)]. They proposed a block cipher algorithm using chaotic Tent map. For the Feistel structure used there are a certain vulnerabilities that can be exploited to find out the rotations the plaintext goes through. For a small number of rounds this can be used to retrieve the plaintext or the key. Hence we have proposed an enhanced algorithm which shows favorable results.